In a known storage phosphor reader, a cassette containing a storage phosphor is located at a cassette receiving station where the cassette is clamped to the reader. A storage phosphor extraction mechanism extracts the storage phosphor from the cassette and moves the storage phosphor onto a stage. The stage moves the storage phosphor past a laser scanning reading station where the latent radiographic image stored in the phosphor is converted to a radiographic image signal.
In order to successfully extract the storage phosphor, the reader must know where the cassette is located to properly position the extraction mechanism. Since there exist a number of different sized cassettes, it becomes critical to adjust for location of the extraction mechanism. Cassettes smaller than 35 cm.times.43 cm require a holding pallet to be successfully fed into the reader. This causes a dimensional difference in cassette location from a datum point.
An extraction mechanism used in such reader includes a hook bar assembly and a locating pin (See: U.S. Pat. No. 5,330,309, issued Jul. 19, 1994, inventors Brahm et al). The assembly is initially moved so that the locating pin contacts the front end of the storage phosphor. The assembly is then moved laterally of the cassette until the locating pin falls into a reference opening in the front end of the storage phosphor. The extractor assembly is then moved relative to the cassette to engage the hook bar assembly with the storage phosphor to unlatch the storage phosphor and to subsequently remove the storage phosphor from the cassette onto a stage. Although this extraction mechanism has been suitable for its intended purpose, it would be desirable to provide a simpler, more reliable, more efficient, and less costly extraction system.